Metallized toy balloons generally comprise two peripherally heat sealed panels, each composed of a composite laminate film layer, such as an exterior layer of aluminum, an intermediate layer of plastic, and an inner layer of heat sealable coating.
Valving devices of various configurations are presently used to ensure a reliable seal on such balloons, as well as on flexible tubing and the like. U.S. Pat. No. 4,674,532 is directed to a four layer valving mechanism comprising a two layer longitudinal pouch-like valve situated within a two layer flat inlet pipe. The entire mechanism is then inserted into the balloon opening. This valve arrangement does suffer several drawbacks. The open base end of the valve actually extends into the container body and flaps freely therein in awkward fashion. Further, the mechanism is formed of four film layers separate from and in addition to the two layers of the container for a total of six film layers. The two valve film layers must be bonded closed at the tip end of the valve before insertion into the container so as to ensure the presence of an inlet passage gap through which fluid may flow. Further the pipe sides must be bonded.
These extra construction steps are undesirable as ease of assembly is an important goal during mass production of balloons. Also, the four layer valve mechanism has excess seal joints which provide increased opportunity for unwanted leaks.
In addition, such valves are installed by heat-seal in the container after the container has been made or by a complex in-line system requiring precise registered location of the valve. They also require printing of a non-heat sealable coating on the inner surfaces of the mechanism.
U.S. Pat. No. 4,708,167 is directed to a check valve virtually identical in operation to the above-described prior art device. Other than the fact that this embodiment comprises only five layers as opposed to six, its drawbacks are the same as those for the U.S. Pat. No. 4,674,532.
Also known in the art are two layer flat pipe valves as described, e. g., in U.S. Pat. No. 3,523,563. Like the four layer valves, the two layer valves extend freely into the interior of the balloon. The two layer valve, which is essentially a flat inlet pipe depends upon the "tackiness" of the film materials which causes the valve to seal closed.
Single-layer flat valves have been described in U.S. Pat. Nos. 2,597,924 and 3,523,563. However, it is essential to these past inventions that the valve surfaces be self-adherent. The necessity for providing surfaces which rely on "tackiness" of the film materials is undesirable in manufacturing operations.
A further important consideration in devices of this type are balloon valve filling systems, which act to terminate the filling operation at a pressure below the bursting pressure of the container. Presently, such systems operate independently of the container itself, and typically consist of a regulator of a low pressure or timed flow design installed at filling locations. These regulators act by slowing the rate of flow into the container as maximum pressure nears, thus decreasing filling time efficiency. Further, the regulators described are costly compared to the balloon materials used.
Experience has shown that the valves described in the prior art do not exhibit sufficient prevention of leaks to provide for consistent prolonged use. Also, the need for expensive pressure regulating equipment has not been overcome by the prior art. The present invention seeks to overcome these and other drawbacks of the prior art valves.
Accordingly, it is an object of the present invention to provide a one layer self-sealing flat valve channel characterized by more reliable, and prolonged and effective leak resistance.
It is a further object to provide a fluid container which need not rely on the self-adherence of the valve surfaces for sealing operation.
It is a still further object to provide a fluid container which prevents overfilling by automatically self-sealing when a desired pressure has been reached without the aid of an outside regulator.
It is a further object to provide a fluid container of simple and inexpensive construction which comprises only a single valve layer which forms an inlet valve channel integral with one of the container surfaces.
It is a still further object to provide a fluid container free of any awkward free-standing extensions situated therein by providing a valve integral with one of the container surfaces.
It is an additional object to provide a self-sealing flat valve which may be formed as part of the fluid container itself during the construction thereof.